1. Field of the Invention
The present invention relates to a tape for cleaning magnetic head of a magnetic recording and reproducing device in which a magnetic recording medium such as an audio tape or a video tape is utilized.
2. Description of Prior Arts
A magnetic recording medium (hereinafter referred to as magnetic tape) such as an audio tape, a video tape or a tape for computer system, comprises a non-magnetic support and a magnetic recording layer containing a ferromagnetic metal oxide powder in the form of needle crystals such as of .gamma.-Fe.sub.2 O.sub.3, Co-containing iron oxide or CrO.sub.2 dispersed in a binder.
Recently, an 8 mm video tape has been developed, and as a result, more high density recording has became required. Accordingly, a magnetic tape containing a ferromagnetic metal powder which has a high coercive force (Hc) and a high residual flux density (Br) becomes more popular than the aforementioned tapes with metal oxide powders.
Further, the material of a magnetic head has been studied for improvement to meet the requirements in relation to the aforementioned development of a magnetic recording medium for high density recording. Thus, a magnetic head of an alloy material such as sendust becomes more popular than the conventional magnetic head of a ferrite material.
Especially as the material of magnetic head used in the 8 mm video recorder, an alloy such as sendust is now widely used for improving the reproduction output. Further, there is a special advantage with a magnetic head of this material; that is, a magnetic tape does not need to be placed under high pressure (the conventional magnetic head of ferrite-forming material needs to be placed under high pressure), whereby the deterioration of a magnetic tape caused by the contact with a running device is reduced.
With the combined use of a magnetic recording medium containing a ferromagnetic metal powder having a high coercive force and a magnetic head of a sendust composite type, it is now possible to fulfill the aforementioned requirements such as those required in the case using an 8 mm video tape system where high density recording and high reproduciton output are necessary.
Nevertheless, there is a problem in the use of a ferromagnetic metal powder. That is, since the ferromagnetic metal powder has a low hardness, the magnetic layer of the magnetic recording medium containing the metal powder does not show a sufficient durableness for running, and the a ferromagnetic metal powder readily drops out of the magnetic recording layer. The ferromagnetic metal powder dropped from the magnetic recording layer causes clogging on the magnetic head, which lowers the reproduction output.
Such clogging on the magnetic head is removed by running the so-called cleaning tape in contact with the surface of a magnetic head. The cleaning tape comprises a support and a cleaning layer containing an abrasive having high hardness. By the use of the cleaning tape, the stain on a magnetic head of a hard ferrite material can be eliminated effectively without damaging the magnetic head. However, a magnetic head of an alloy material such as sendust having a low hardness and a very smooth surface is readily injured by the contact of the conventional cleaning tape. The injured surface of a magnetic head causes noise generation and drop-out in the output process. Therefore, a new cleaning tape which solves this problem is required.